ive got an 86 rx7 s4 na. its been sitting a year. fired it up today and now the idle is fluctuating. any thing helps.

 

welcome to the board.

here is a link for you to get a copy of the FSM: Foxed.ca

it could be (any one of) a few things. so you can check the following:
vacuum leak
temperature sensor for the ECU
TPS

 

After sitting for a year, it's likely that your fuel is stale. You didn't mention whether or not you replaced the fuel. Stale fuel will cause poor idle. Also, your injectors might be partially clogged, which will also lead to poor idle. Your injectors are seated in the intake manifold with a rubber insulator. Over time, that rubber will deteriorate and may cause a vacuum leak, which will cause poor idle, Could be many things causing your poor idle, but I'd start by looking at these first.

 

bac valve could also be gummed up. test it with a 9vbattery like you would w fuel injectors. if it aint movin give it some brakekleen in the piston till it does